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Discussion Starter #1
My misbehaving 95 164 LS 5 speed (151k miles) has finally decided to store a CEL code after months of no code but poor performance. It is giving me a 1224 code, which is "Failed Lambda probe". My question is whether there is anything else that can give this code before I go dropping $200 to Jason or whomever for a new O2 sensor.

Symptoms are that the car starts fine from hot or cold, never threatens to stall, but has a misfire that ranges from subtle to downright violent. Idle is rough too. Basically, if I am driving at a steady speed it feels like the ignition is cutting in and out, and if I press the gas it sometimes feels like the car bogs down and then surges forward.

I pulled the connector for the O2 sensor apart with the car running and stuck a meter on it. The output stays constant no matter what you do, like purposely inducing an air leak by pulling the dipstick.

Yes, I did take apart and clean all the major connectors I could find. I even cleaned the MAS since the black plastic cover was loose anyway.

TIA

Arno
 

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sounds like tramp air leak

TO me it sounds like you are getting air leaking into the intake thats not going thru the AFM. Your 1224 code is saying that the ECU cant adjust enough to bring the lambda sensor into proper range.

Check your hose from AFM to plenum for cracks. Check the idle air actuator for tightness. Check the intake runners for leaks. Take some brake cleaner and spray it all around these items to see if you can detect any change in engine noise/rpm. Check your dog bone and engine side mount (top).

Check your fuel pressure too. If you have a weak or underpressurized fuel system its the same as too much air-- results in a lean mix.

Your symptoms are also somewhat consistent with arcing coil packs. TAke the front cover off and watch in the dark to see if there are any blue sparks. Listen to the rear and front to see if there is any 'snapping' sound. Check the injectors to see if you can feel them 'click' -- lots of sensory checking you can do without much more than your 5 senses!
 

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Discussion Starter #3
I will check the coil packs. That was my first thought but local mechanic swears that they are not the problem. I have checked all the hoses etc for leaks and can't find any. All engine mounts were replaced in the last year and a half or so. I will check the idle gizmo again now that you mention it. I had to remove it for a different issue a while back, and they don't fit tightly in the best of times.

How do you check the rear bank of coil packs since the intake has to come off to remove the rear cover?
 

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thats a great question

what I do is insure that the front ones are good -- then I pull the plenum, and swap fronts for rears (after I check plug gaps in the rears!) then put it all back together -- so now I know i have good coils in the back.

Also check the condition / connections of the ignition modules under the cruise control apparatus.
 

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Discussion Starter #5
Thanks Goats. That makes perfect sense.
 
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